vendor/salsa/tests/parallel/frozen.rs

   1 use crate::setup::{ParDatabase, ParDatabaseImpl};
   2 use crate::signal::Signal;
   3 use salsa::{Database, ParallelDatabase};
   4 use std::sync::Arc;
   5
   6 /// Add test where a call to `sum` is cancelled by a simultaneous
   7 /// write. Check that we recompute the result in next revision, even
   8 /// though none of the inputs have changed.
   9 #[test]
  10 fn in_par_get_set_cancellation() {
  11     let mut db = ParDatabaseImpl::default();
  12
  13     db.set_input('a', 1);
  14
  15     let signal = Arc::new(Signal::default());
  16
  17     let thread1 = std::thread::spawn({
  18         let db = db.snapshot();
  19         let signal = signal.clone();
  20         move || {
  21             // Check that cancellation flag is not yet set, because
  22             // `set` cannot have been called yet.
  23             assert!(!db.salsa_runtime().is_current_revision_canceled());
  24
  25             // Signal other thread to proceed.
  26             signal.signal(1);
  27
  28             // Wait for other thread to signal cancellation
  29             while !db.salsa_runtime().is_current_revision_canceled() {
  30                 std::thread::yield_now();
  31             }
  32
  33             // Since we have not yet released revision lock, we should
  34             // see 1 here.
  35             let v = db.input('a');
  36
  37             // Since this is a snapshotted database, we are in a consistent
  38             // revision, so this must yield the same value.
  39             let w = db.input('a');
  40
  41             (v, w)
  42         }
  43     });
  44
  45     let thread2 = std::thread::spawn({
  46         let signal = signal.clone();
  47         move || {
  48             // Wait until thread 1 has asserted that they are not cancelled
  49             // before we invoke `set.`
  50             signal.wait_for(1);
  51
  52             // This will block until thread1 drops the revision lock.
  53             db.set_input('a', 2);
  54
  55             db.input('a')
  56         }
  57     });
  58
  59     let (a, b) = thread1.join().unwrap();
  60     assert_eq!(a, 1);
  61     assert_eq!(b, 1);
  62
  63     let c = thread2.join().unwrap();
  64     assert_eq!(c, 2);
  65 }